<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        ul {
            margin: 200px;
            /* perspective: 1000px; */
        }
        ul li {
            float: left;
            width: 80px;
            height: 30px;
            margin-right: 30px;
            list-style: none;
            transform-style: preserve-3d;
            transition: all 0.4s;
        }
        .qian {
            width: 80px;
            height: 30px;
            background-color: orange;
            transform: translateZ(16px);
            z-index: 1;
        }
        .shang {
            width: 80px;
            height: 30px;
            background-color: purple;
            transform: translateY(-17px) rotateX(-90deg);           
        }
        li:hover {
            transform: rotateX(90deg);
        }
    </style>
</head>
<body>
    <ul>
        <li>
            <div class="box">
                <div class="qian">666</div>
                <div class="shang">777</div>
            </div>
        </li>
        <li>
                <div class="box">
                <div class="qian"></div>
                <div class="shang"></div>
            </div>
        </li>
        <li>
            <div class="box">
                <div class="qian"></div>
                <div class="shang"></div>
            </div>
        </li>
        <li>
            <div class="box">
                <div class="qian"></div>
                <div class="shang"></div>
            </div>
        </li>
        <li>
            <div class="box">
                <div class="qian"></div>
                <div class="shang"></div>
            </div>
        </li>
    </ul>  
</body>
</html>